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Mr Biffen, Note on some factors in the 
Note on some factors in the spore- formation of Acrospeira 
mirabilis (Berk, and Br.). By R. H. Biffen, B.A., Emmanuel 
College. 
[Bead 4 March 1901.] 
Acrospeira mirabilis is a fungus found as a parasite on Spanish 
chestnuts 1 and so far nothing beyond the mode of development of 
its characteristic chlamydospores, traced by Berkeley in 1861, has 
been published. 
This note on some of the factors concerned in its spore- 
formation is but a portion of the results obtained while making 
the attempt to trace its life history and so to find its true place in 
the present system of classification. 
The spores found by Berkeley and Broome were developed 
from the subterminal cell of a row of three or four, coiled into a 
spiral of from one and a half to two turns. These cells all became 
fused together so that the spore was partially invested. When 
ripe it was brown, thick-walled, and covered with rounded warts. 
The investing cells were similar, but thinner-walled and poor in 
protoplasmic contents. 
From its thick walls one might conclude that this spore-form 
was a resting-spore like the chlamydospores (or paulospores of 
Klebs) of Hypomyces spp. but it seems to be the spore-form which 
serves for the rapid reproduction of the fungus. 
In spite of the fact that Acrospeira is a parasite it may be 
grown readily as a saprophyte on various media. On germination 
the large cell only puts out a hypha, the further development of 
which was determined chiefly by the food supply available. 
Thus if sown on an extract of peas and ten per cent, gelatine 
the mycelium grew slowly and remained sterile altogether, though 
transferred repeatedly to fresh supplies of pea extract. If however 
it was transferred to pieces of sterilized chestnuts it gave rise, in 
the course of four or five days, to numbers of the invested 
chlamydospores, similar to those described by Berkeley. 
On sowing on slices of sterilized melon chlamydospores were 
again formed but a large percentage of them were abnormal and 
resembled the teleutospores of Puccinia or of Pliragmidium in 
shape, owing to the development of two or of three of the cells to 
form spores without the preliminary coiling. 
1 Berkeley and Broome, Anns, and Mag. Nat. Hist., 1861, p. 449. 
